Baby with sudden rash?

Dd is 11 months. Was very unsettled overnight friday, then irritable next day. Around 2pm I noticed a bright red rash on one upper arm & also on opposite leg (had not been there at 11am previous change). Hot to touch. Arm rash was gone an hour or so later, leg faded over next few hours. Again super unsettled overnight but no rash - then early afternoon today we literally saw red rash appear suddenly on bubs cheek (only one) it was hot to touch like yesterday & lasted 1-2 hours. No temperature. Rash doesn't particularly bother her but still generally irritable.